The graphic arts industry is concerned with trimming the edges of signatures which are used to form magazines, books, and the like. The trimming provides for the neat and accurate alignment of the edges of the pages in the signatures, and this commonly requires that the signatures be cut or trimmed to provide the neat and aligned edges.
U.S. Pat. Nos. 974,198 and 4,511,131 show prior trimming devices where signatures or the like are moved over a cylinder or roller while a disk type of cutter or trimmer is applied to the signatures on the cylinder or roller, all for removing the marginal edges of the signatures in the trimming process. That type of apparatus requires that the cutter or trimmer itself be a movable blade, and, in those instances, it requires that the blade be rotatably mounted in proximity to the roller or cylinder for rolling therewith during the trimming process. U.S. Pat. No. 4,496,140 shows a signature trimmer wherein the signatures are individually deposited into a rotation device which moves the signatures passed stationary cutters for trimming the edges of the signature.
In the prior art, such as that mentioned, the trimmer is required to be either a movable disk for cooperative rotation with a base cylinder or roller, as mentioned above, or it is required to be a fixed blade which can trim signatures when they are separately presented to the blade. The present invention differs from the prior art in that it provides for a method and apparatus of trimming signatures which are disposed in a continuous stream of overlapped signatures moving in an arcuate path and against a stationary knife, all for trimming one edge or the opposite edges from the stream of signatures in the continuous movement of the signatures. As such, the present invention improves upon the prior art in providing for the neat and arcuate trimming of the signatures which are continuously moving in the common type of conveyance of signatures, namely, in an arcuate path and constrained by conveyors formed by belts or the like, and thus only a stationary knife is required adjacent the arcuate path for engagement of the signatures in the trimming process. As such, the present invention simulates a trimming process of the nature of scissors or a conventional cutter in that there is a flat lead-in approach of the signatures to the trimmer itself. That is, the trimmer of this invention provides for a very shallow angle of trimming to present the cutting edge in the nature of a conventional cutter while still moving the signatures in a continuous path past the cutter and not requiring that the cutting edge itself be moved or that the signatures be stopped for the cutting process. In this invention, the approach angle for cutting is in the nature of a crescent shape opening into which the signatures move and thereby encounter the very small angle of cutting, as is most desirable.
Still further, the present invention provides for the trimming of the opposite sides of signatures in a simultaneous trimming process, and also a third side of the signatures can be readily trimmed in the same manner after the signatures are moved from the first trimmer and to a second trimmer or cutting edge arranged in the same manner as the first trimmer is arranged. In all, the signatures continue to move and thus the desired high production is achieved throughout the conveying and trimming process.